1. Field
One or more embodiments of the present invention relate to a negative active material, an electrode including the same, and a lithium battery including the electrode.
2. Description of the Related Art
Recently, lithium secondary batteries have drawn attention as power sources for small, portable electronic devices. As lithium secondary batteries contain an organic electrolyte solution, they have a discharge voltage that is at least two times that of batteries containing an aqueous alkali electrolyte, and thus lithium secondary batteries have a higher energy density.
As positive materials for lithium secondary batteries, lithium-transition metal oxides, such as LiCoO2, LiMn2O4, and LiNi1-x-yCOxMnyO2 where 0≦x≦0.5 and 0≦y≦0.5, which have a structure that allows intercalation of lithium ions, are mainly used. Carbonaceous materials in various forms, such as artificial graphite, natural graphite, and hard carbon, which allow intercalation and deintercalation of lithium ions, have been used as negative materials. In order to develop high-capacity and high-output batteries, non-carbonaceous materials, such as silicon (Si), SiOx, or an Si/Sn alloy, have also been intensively studied for use as negative materials.
Such non-carbonaceous materials exhibit a very high capacitance density at least ten times that of graphite. However, due to volumetric expansion and shrinkage of a non-carbonaceous material during charging and discharging of a lithium battery, the cycle lifetime characteristics of the battery may deteriorate. Furthermore, there are difficulties in handling such non-carbonaceous materials during manufacturing processes.